Stability and accuracy of spatial approximations for wave equation tidal models

Amplitude and phase characteristics for numerical approximations to the shallow water wave equation are obtained for linear and quadratic finite elements, for finite difference approximations, for non-constant bathemetry, and for uneven node spacing. Stability is shown to require non-zero friction as well as satisfaction of a Courant constraint. Lumping is shown to reduce the Courant constraint for stability while higher order and quadratic finite element approximations require a more restrictive constraint than their second order and linear finite element counterparts. The amplitude of the propagation factor for stable schemes and propagating waves is seen to be independent of the Courant number and type of numerical approximation. Although the higher order and quadratic schemes provide better propagation of the low and moderate frequency waves, the highest frequency waves (2Δx) are better propagated by low order numerical methods.     

Parton showers in leptoproduction events

We present a model that includes the production of arbitrarily many jets in lepton-hadron events, using the leading log formalism for parton shower evolution. The main problem encountered here, which has not previously been illuminated by studies ofe ⁺ e ^? annihilation or Drell-Yan/Z ⁰/W ^± production, is the choice of kinematics in the space-like shower evolution. In our preferred solution, the standard definition of Bjorkenx is preserved during the construction of initial and final state showers—a nontrivial constraint. The resulting model is described in detail, including some first investigations of its properties.     

Soot-visualization strategies using laser techniques

Strategies for spatially resolved soot volume-fraction measurements have been investigated in sooting laboratory flames with known soot characteristics. Two techniques were compared: Laser-Induced Fluorescence in C₂ from Laser-Vaporized Soot (LIF(C₂)LVS), and Laser-Induced Incandescence of soot (LII). The LII signal is the increased temperature radiation from soot particles which have been heated to temperatures of several thousand degrees as a consequence of absorption of laser radiation. The LIF(C₂)LVS technique is based on the production of C₂ radicals from laser-vaporized soot which occurs for laser intensities ≥10⁷ W/cm². A laser wavelength is chosen such that besides vaporizizng the soot, it also excites the C₂ radicals, and the subsequent C₂ fluorescence signal is detected. The signals from both techniques showed good correlation with soot volume fractions in the studied flame. The dependence of the signals on experimental parameters was studied, and the influence of interfering radiation, such as background flame luminosity and fluorescence from polyaromatic hydrocarbons, on studied signals was established. The potential of the two techniques for imaging of soot volume fractions in laboratory flames was demonstrated. Advantages and disadvantages of the studied techniques are discussed.     

Finding the 3-gluon vertex from 4-jet events ine + e − annihilation

General properties of single transversee ^± beam polarization asymmetries (cos ? or sin ? azimuthal distributions and their forward-backward asymmetries) are established. These asymmetries are genuine ways of analyzing the structure of chirality violating amplitudes at high energy. Several examples of chirality violating processes are considered and their asymmetries computed. Constraints due tog _e ?2,d _e andm _e are obtained in the form of sum rules and their physical consequences are discussed.     

Adsorption of a tripeptide on platinum electrodes: I. Ac admittance measurements

The tripeptide Bz-Phe-Val-Arg-pNA adsorbs reversibly to platinum electrodes. We show how it is possible to determine the coverage of the tripeptide by measuring the electrode capacitance at a single frequency. The frequency dispersion of the electrode admittance fits a mathematical model with only two adjustable parameters. The model is based on a dispersion of time constants for the electrical events taking place at the electrode. Tunnelling is suggested to be a possible cause of such a dispersion.     

Loss of alignment gain in the πh 9/2[541 1/2−] ⊗ (νi 13/2)2 band in 167Tm and neighbouring odd-Z N = 98 nuclei

Theπh_9/2[541 1/2^?] band in ¹⁶⁷Tm has been studied through the ¹²⁴Sn(⁴⁸Ca, p4n)¹⁶⁷Tm reaction at E _beam = 210 MeV. The favoured signature of the πh_9/2[541 1/2^?] band is observed to spin 61/2h?. A remarkable small gain in aligned angular momentum at the AB-band crossing has been found. The crossing frequency and the gain in aligned angular momentum for ¹⁶⁷Tm are compared with data for the N = 98 isotones of Lu, Ta and Re, and contrasted with Cranked Shell Model predictions, based on frequency diabatic configurations. Large deviations are found for the gain in aligned angular momentum.     

Competition between (h11/2)2 proton and neutron excitations around128Ba: Coexistence of near prolate and near oblate shapes at high spin

Recent cranked shell model calculations give a possible explanation for the occurrence of two S-bands in Ba-nuclei.     

Microscopic study of the high-spin behaviour in selected A ≃ 80 nuclei

The collective and non-collective high-spin configurations in selected $\text{A ? 80}$ nuclei are analysed in detail using a shell-correction approach taking care of individual configurations and the pairing self-consistent cranking method with a non-axially-deformed Woods-Saxon potential. Shape transitions, shape coexistence, band-termination effects and alignment processes are discussed.     

Neighbours of Einstein's equations: Connections and curvatures

Once the action for Einstein's equations is rewritten as a functional of anSO(3, ) connection and a conformal factor of the metric, it admits a family of neighbours having the same number of degrees of freedom and a precisely defined metric tensor. This paper analyzes the relation between the Riemann tensor of that metric and the curvature tensor of theSO(3) connection. The relation is very complicated in general. The Einstein case is distinguished by the fact that two naturalSO(3) metrics on theGL(3) fibres coincide. In the general case the theory is bimetric on the fibres.